Automatic drainage device for small pit

Abstract

The utility model relates to an automatic drainage device for a small pit, which comprises a first support, a second support, a first distribution box, a second distribution box and a submersible pump, the first support, the second support, the first distribution box and the second distribution box are mounted on the surface of a wall, the submersible pump is arranged in the ground pit, a low-voltage float switch positioned on the inner side of the pit is mounted on the first support, and a filter component is arranged on the second support. And a first controller electrically connected with the low-voltage float switch and a time relay electrically connected with the first controller and the submersible pump are arranged in the first distribution box. The design of the low-voltage floating ball switch and the time relay is adopted, timely pumping of waste water is guaranteed, damage to the submersible pump is avoided, meanwhile, damage to the submersible pump is effectively avoided by means of the backwashing structure and the audible and visual alarm, normal operation of the submersible pump is facilitated, the service life is guaranteed, and the service life of the submersible pump is prolonged. By means of the design of the water collecting tank, impurities can be cleaned, backwashing sewage can be extracted along with waste water, and certain practicability is achieved.

Description

Technical Field

[0001] The utility model relates to the technical field of drainage, in particular to an automatic drainage device for a small pit. Background Art

[0002] Sludge is a thick substance between liquid and solid, with a high organic matter content. It is easy to rot and stink, and has a great impact on the atmospheric environment. Therefore, municipal sewage treatment plants are needed to treat sludge. During the sludge treatment process, a certain amount of wastewater will be generated, including the water carried by the sludge itself and the filtrate generated during the treatment process. In order to prevent the wastewater from flowing everywhere and causing water accumulation and pollution in the factory area, municipal sewage treatment plants mainly use pits to collect these wastewaters, and then transport them to the wastewater treatment system through special pipes for further treatment.

[0003] Currently, most sewage treatment plants use square level float switches to control pumps for wastewater extraction from pits. However, for some sewage treatment plants collecting wastewater from small pits, the square level float switch requires a long response stroke (requiring a water level rise of approximately 30 cm) for the steel ball to activate each microswitch. This long response stroke can cause wastewater in the pit to overflow and cause water accumulation and pollution within the plant. Furthermore, when the water level drops, the square level float switch switches contact points immediately, resulting in a shorter operating time for the pump. This reduces the amount of wastewater extracted from the pit, shortening the time between the next pump start and the next. This frequent starting and stopping can shorten the pump's service life. Furthermore, when the submersible pump is pumping wastewater for extended periods, impurities or debris in the wastewater can cause internal blockage, preventing the pump from operating normally. This not only affects the discharge of wastewater from the pit, but can also cause the submersible pump motor to overheat and burn out due to the increased power output. Utility Model Content

[0004] The utility model provides an automatic drainage device for a small pit, so as to solve the problems raised in the above background technology.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] A small pit automatic drainage device comprises a first bracket mounted on the wall surface, a second bracket, a first distribution box and a second distribution box, and a submersible pump arranged in the ground pit, the first bracket is fixedly mounted with a low-pressure float switch located inside the pit, the second bracket is provided with a filter assembly, and the first distribution box is provided with a first controller electrically connected to the low-pressure float switch and a time relay electrically connected to the first controller and the submersible pump, the water inlet of the submersible pump is connected to a water suction pipe and a backwash outlet pipe through a tee pipe, the water suction pipe is provided with a first solenoid valve, and the backwash outlet pipe is provided with a first solenoid valve. A second solenoid valve is installed on the flushing outlet pipe, one end of the backwash outlet pipe is arranged above the filter assembly, and the water outlet of the submersible pump is connected to a sewage pipe, and a pressure sensor is provided on the sewage pipe. The end of the sewage pipe away from the water outlet of the submersible pump is connected to a sewage pipe and a backwash inlet pipe through a three-way pipe, a third solenoid valve is installed on the sewage pipe, and a fourth solenoid valve is installed on the backwash inlet pipe, and a second controller electrically connected to the pressure sensor, the first solenoid valve, the second solenoid valve, the third solenoid valve and the fourth solenoid valve is provided in the second distribution box.

[0007] Preferably, the filter assembly includes a water collecting tank installed on the second bracket, a filter plate arranged in the water collecting tank, a return pipe connected to the bottom of the water collecting tank, and a fifth solenoid valve installed on the return pipe, and the fifth solenoid valve is electrically connected to the second controller, and one end of the backwash outlet pipe is arranged at the opening at the top of the water collecting tank.

[0008] Preferably, the inner cavity of the water collecting tank is provided with an inclined ramp, the bottom of the filter plate is inserted into the inclined ramp, and the inner cavity of the water collecting tank is divided into a first chamber and a second chamber by the filter plate, one end of the backwash outlet pipe is provided at the opening of the first chamber, and one end of the return water pipe is connected to the second chamber.

[0009] Preferably, a guide groove is provided on the inner wall of the water collecting box, the filter plate is arranged in the guide groove, and a handle is connected to the top of the filter plate.

[0010] Preferably, a small pit automatic drainage device also includes a power storage device installed on the wall surface and solar panels distributed on the roof, and the power storage device is electrically connected to the solar panels, the first controller and the second controller respectively.

[0011] Preferably, an audible and visual alarm is fixedly installed on the top of the second distribution box, and the audible and visual alarm is electrically connected to the second controller.

[0012] Preferably, the pit includes a water flow section and a circular groove area, the submersible pump is arranged in the circular groove area, and a recessed groove is provided in the circular groove area, and one end of the water suction pipe is arranged in the recessed groove.

[0013] Preferably, the low-pressure float switch is arranged in the water flow section, and the model of the low-pressure float switch is P45 low-pressure float switch.

[0014] Preferably, one end of the backwash water inlet pipe is connected to a high-pressure water pump, and the water inlet of the high-pressure water pump is connected to a clean water tank through a pipeline.

[0015] Preferably, a wire threading tube for wiring is provided on the surface of the wall.

[0016] By adopting the above technical solution, the beneficial effects achieved by the utility model are as follows:

[0017] In the utility model, through the cooperation of the submersible pump, the low-pressure float switch and the time relay, after the low-pressure float switch is floated by the buoyancy of the wastewater, it can prompt the first controller to control the submersible pump to work according to the signal, thereby ensuring timely extraction of wastewater. After the submersible pump is working, with the help of the design of the time relay, the first controller can shut down the submersible pump according to the end of the time relay after each start of the submersible pump, effectively extending the operation of the submersible pump, ensuring that the water level in the pit will drop significantly after each extraction, effectively reducing the frequent start and stop of the submersible pump, and ensuring the service life of the submersible pump.

[0018] In the utility model, when the pressure sensor monitors that the pressure in the sewage pipe is abnormally reduced, the second controller can receive the signal and control the first solenoid valve and the third solenoid valve to close and control the fourth solenoid valve and the second solenoid valve to open. In this way, when the high-pressure water pump is working, clean water can follow the pipeline to perform high-pressure backwashing on the submersible pump, thereby achieving the effect of cleaning the inside of the submersible pump, ensuring the normal operation of the submersible pump, and avoiding damage to the submersible pump.

[0019] In the utility model, through the design of the water collecting tank, after the high-pressure backwash is completed, the sewage can flow into the water collecting tank, and then the sewage in the water collecting tank can be discharged into the pit through the return pipe, which is conducive to the extraction and treatment of sewage together with wastewater. The design of the filter plate when the sewage is discharged can achieve that impurities or debris are blocked and retained in the first chamber, preventing the dirt from causing clogging of the submersible pump again, and the blocked dirt can be manually cleaned regularly to ensure normal filtering work in the water collecting tank, which has certain practicality.

[0020] In the utility model, through the design of the sound and light alarm, when the pressure sensor detects abnormal pressure in the sewage pipe multiple times in a short period of time, the second controller can control the sound and light alarm to alarm, so as to warn the staff to check and repair in time, avoid the submersible pump from being blocked, and cause the wastewater to overflow and flow everywhere due to untimely discharge. At the same time, it also avoids damage to the submersible pump and ensures the normal service life of the submersible pump.

[0021] In summary, the utility model adopts the design of low-pressure float switch and time relay, which not only ensures the timely extraction of wastewater, but also avoids damage to the submersible pump. At the same time, with the help of backwash structure and sound and light alarm, it also effectively avoids damage to the submersible pump, which is beneficial to the normal operation of the submersible pump and ensures its service life. The design of the water collecting tank not only realizes the cleaning of impurities, but also realizes the extraction and treatment of backwash sewage together with wastewater, which has certain practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the overall structure of the utility model.

[0023] Figure 2 It is a left-side structural schematic diagram of the present invention.

[0024] Figure 3 It is a partial three-dimensional structural diagram of the utility model.

[0025] Figure 4 for Figure 3 Schematic diagram of the rear cross-section of part of the three-dimensional structure.

[0026] Figure 5 This is a circuit diagram of the utility model.

[0027] In the figure: 1. First bracket; 2. Second bracket; 3. First distribution box; 4. Second distribution box; 5. Pit; 6. Submersible pump; 7. Low-pressure float switch; 8. First controller; 9. Time relay; 10. Suction pipe; 11. Backwash outlet pipe; 12. Sewage pipe 1; 13. Pressure sensor; 14. Sewage pipe 2; 15. Backwash inlet pipe; 16. Second controller; 17. Water collecting tank; 18. Filter plate; 19. Return pipe; 20. First chamber; 21. Second chamber; 22. Power storage device; 23. Solar panel; 24. Sound and light alarm; 100. First solenoid valve; 110. Second solenoid valve; 140. Third solenoid valve; 150. Fourth solenoid valve; 190. Fifth solenoid valve. DETAILED DESCRIPTION

[0028] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described below with reference to the accompanying drawings and embodiments. It should be noted that the embodiments of the present application and the features therein can be combined with each other without conflict.

[0029] In the present invention, the term "plurality" refers to two or more than two, unless otherwise expressly defined. The term "and / or" used herein includes any and all combinations of one or more of the relevant listed items. Terms such as "installation", "connection", "connection", and "fixed" should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; "connection" can be a direct connection or an indirect connection through an intermediate medium. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0030] It should be noted that when an element is referred to as being "assembled to," "mounted to," "fixed to," or "disposed on" another element, it may be directly on the other element or there may be an intermediate element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only implementation methods.

[0031] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways than those described herein. Therefore, the present invention is not limited to the specific embodiments disclosed in the following specification.

[0032] like Figure 1-Figure 5As shown, the utility model provides an automatic drainage device for a small pit, comprising a first bracket 1 mounted on the wall surface, a second bracket 2, a first distribution box 3 and a second distribution box 4, and a submersible pump 6 arranged in a pit 5 on the ground. A low-pressure float switch 7 located inside the pit 5 is fixedly mounted on the first bracket 1, a filter assembly is provided on the second bracket 2, and a first controller 8 electrically connected to the low-pressure float switch 7 and a time relay 9 electrically connected to the first controller 8 and the submersible pump 6 are provided in the first distribution box 3. The water inlet of the submersible pump 6 is connected to a water suction pipe 10 and a backwash outlet pipe 11 through a tee pipe. A first solenoid valve 100 is installed on the water suction pipe 10, and the backwash outlet A second solenoid valve 110 is installed on the pipe 11, one end of the backwash outlet pipe 11 is arranged above the filter assembly, and the water outlet of the submersible pump 6 is connected to a sewage pipe 12, and a pressure sensor 13 is provided on the sewage pipe 12. The end of the sewage pipe 12 away from the water outlet of the submersible pump 6 is connected to a sewage pipe 14 and a backwash inlet pipe 15 through a three-way pipe, a third solenoid valve 140 is installed on the sewage pipe 14, and a fourth solenoid valve 150 is installed on the backwash inlet pipe 15, and a second controller 16 electrically connected to the pressure sensor 13, the first solenoid valve 100, the second solenoid valve 110, the third solenoid valve 140 and the fourth solenoid valve 150 is provided in the second distribution box 4.

[0033] Furthermore, the filter assembly includes a water collecting tank 17 installed on the second bracket 2, a filter plate 18 arranged in the water collecting tank 17, a return pipe 19 connected to the bottom of the water collecting tank 17, and a fifth solenoid valve 190 installed on the return pipe 19, and the fifth solenoid valve 190 is electrically connected to the second controller 16, one end of the backwash outlet pipe 11 is arranged at the opening at the top of the water collecting tank 17, the inner cavity of the water collecting tank 17 is provided with an inclined ramp, and a positioning groove is provided on the inclined surface of the inclined ramp. The bottom of the filter plate 18 is inserted into the positioning groove on the inclined ramp, and the inner cavity of the water collecting tank 17 is divided into a first chamber 20 and a second chamber 21 by the filter plate 18. The inclined ramp takes the inner bottom wall of the first chamber 20 as the high point, and gradually tilts downward from the high point of the first chamber 20 to the low point of the second chamber 21. One end of the backwash outlet pipe 11 is arranged at the opening of the first chamber 20, and one end of the return pipe 19 is connected to the second chamber 21.

[0034] Specifically, the design of the water collecting tank 17 allows the backwash sewage to flow into the water collecting tank 17 through the backwash outlet pipe 11, and then the sewage is filtered through the filter plate 18, and the impurities or debris can be filtered out in the first chamber 20, so that the sewage can flow into the second chamber 21 after passing through the filter plate 18, so that after the fifth solenoid valve 190 is opened, the sewage in the second chamber 21 can be discharged into the pit 5 through the return pipe 19.

[0035] Furthermore, a guide groove is provided on the inner wall of the water collecting box 17 , the filter plate 18 is arranged in the guide groove, and a handle is connected to the top of the filter plate 18 .

[0036] Specifically, the guide grooves are opened correspondingly on the two parallel side walls of the water collecting box 17, and the two guide grooves are connected to the positioning grooves on the inclined ramp, and the cross-sections of the two guide grooves and the positioning grooves are "U"-shaped; and the design of the handle on the filter plate 18 facilitates the insertion and removal of the filter plate 18.

[0037] In this embodiment, a small pit automatic drainage device also includes a power storage device 22 installed on the wall surface and a solar panel 23 distributed on the roof. The power storage device 22 is electrically connected to the solar panel 23, the first controller 8 and the second controller 16 respectively, and the power storage device 22 and the solar panel 23 are electrically connected through an inverter.

[0038] Specifically, in actual operation, an inverter needs to be installed between the power storage device 22 and the solar panel 23. Since the use of inverters is well known and applied by those skilled in the art, this article does not provide a detailed description of the circuit part between the power storage device 22 and the solar panel 23, nor does it provide diagrams. However, it should be emphasized that although this article does not elaborate in detail, in actual use, an inverter needs to be installed between the power storage device 22 and the solar panel 23.

[0039] To be more specific, through the design of the power storage device 22, the power storage device 22 can supply power in time to the first controller 8 and the second controller 16 when a normal circuit fails, ensuring a certain amount of power supply in an emergency, thereby ensuring the normal discharge of wastewater in the pit 5, and avoiding the overflow of wastewater and the problem of water accumulation and pollution in the factory area.

[0040] Furthermore, an audible and visual alarm 24 is fixedly installed on the top of the second distribution box 4 , and the audible and visual alarm 24 is electrically connected to the second controller 16 .

[0041] Specifically, the sound and light alarm 24 can generate an alarm based on the analysis data of the second controller 16 to remind maintenance personnel to check the submersible pump 6 to ensure the normal operation of the submersible pump 6 and the normal discharge of wastewater in the pit 5.

[0042] More specifically, the pressure sensor 13 is used to monitor the pressure of the submersible pump 6 and transmit the monitored data to the second controller 16. After receiving the data, the second controller 16 can perform data analysis and processing, thereby controlling the first solenoid valve 100, the second solenoid valve 110, the third solenoid valve 140 and the fourth solenoid valve 150 through the analysis of the data, so that the fourth solenoid valve 150 and the second solenoid valve 110 are opened when the first solenoid valve 100 and the third solenoid valve 140 are closed, ensuring that clean water can be input into the backwash inlet pipe 15 to complete the high-pressure backwash of the submersible pump 6; and each time After high-pressure backwashing, the second controller 16 can control the fourth solenoid valve 150 and the second solenoid valve 110 to close, and control the first solenoid valve 100 and the third solenoid valve 140 to start, so that the submersible pump 6 can work normally after backwashing. When the pressure sensor 13 still detects abnormal pressure, the second controller 16 can receive the monitoring data of the pressure sensor 13 again, and synchronously control the sound and light alarm 24 to alarm, reminding maintenance personnel to handle it. It should be emphasized that this application only provides a set of physical architecture for realizing automatic drainage of small pits, and does not involve the protection of logical algorithms. The introduction of the system proposed in this article is only for a supplementary explanation of the feasibility and authenticity of this application, and does not require protection for the systematic technology; although this article only briefly mentions the introduction of the system without detailed explanation, the system technology is already a well-known public technology and can be known and applied by those skilled in the art.

[0043] Furthermore, the pit 5 includes a water flow section and a circular groove area. The submersible pump 6 is arranged in the circular groove area, and a recessed groove is provided in the circular groove area. One end of the suction pipe 10 is arranged in the recessed groove, and the low-pressure float switch 7 is arranged in the water flow section.

[0044] Specifically, the pit 5 proposed in this application is close to the edge of the wall according to the actual situation of the factory, and the wastewater is collected and flows through the water flow section. Finally, the wastewater flows concentratedly in the circular trough area, and the depth of the circular trough area is lower than the depth of the water flow section, and the depth of the recessed trough is lower than the depth of the circular trough area, so as to facilitate the wastewater to flow in the recessed trough for extraction.

[0045] Furthermore, the model of the low-pressure float switch 7 adopts a P45 low-pressure float switch. By replacing the square liquid level float switch with a small low-pressure float switch 7, the stroke of the low-pressure float switch 7 is short (about 5 cm) and the floating stroke is small. It can quickly control the submersible pump 6 to extract the wastewater in the pit 5 according to the sensing signal, thereby avoiding overflow of the wastewater in the pit. At the same time, with the cooperation of the low-pressure float switch 7 and a time relay 9, the submersible pump 6 can be turned off by the countdown set by the time relay 9 each time the low-pressure float switch 7 is turned on, thereby ensuring the increase of the drainage work of the submersible pump 6, reducing the frequent start-up and stop, and avoiding frequent start-up and stop to reduce the service life of the submersible pump 6.

[0046] As a further feature, one end of the backwash water inlet pipe 15 is connected to a high-pressure water pump, and the water inlet of the high-pressure water pump is connected to a clean water tank through a pipeline.

[0047] Specifically, the high-pressure water pump and the clean water tank are both existing technologies, which are not illustrated in this article. Although they are not illustrated in this article, those skilled in the art can be familiar with and apply them based on common sense. They are mainly connected through the water inlet of the high-pressure water pump and the clean water tank, and the water outlet of the high-pressure water pump is connected to the backwash inlet pipe 15. When backwashing is required, the opening of the fourth solenoid valve 150 can enable the high-pressure water pump to work and transport clean water for backwashing. It should be noted that the high-pressure water pump here needs to be electrically connected to the second controller 16 to ensure normal circuit control, and because this article only seeks to protect the physical structure and does not protect the circuit system technology, this article does not elaborate on the circuit system part. It should be noted that although this article does not elaborate in detail, those skilled in the art can implement it in conjunction with the physical structure of this article based on the basic circuit system common sense in this field.

[0048] Furthermore, the surface of the wall is provided with a wire conduit for routing wires, which is used to organize the lines between various devices and ensure the safety of electricity use.

[0049] The working principle and use process of this utility model:

[0050] Before use, factory wastewater will flow into the circular trough area and the sunken trough along the flow section of the pit 5. When the wastewater is full in the sunken trough and the circular trough area, the water level will rise synchronously in the circular trough area and the flow section.

[0051] During use, the solenoid valves on the wastewater discharge pipe are in the open state, while the solenoid valves on the backwash pipe and the solenoid valves on the return pipe 19 are in the closed state. Therefore, when the water level in the flow section rises to a certain height, the low-pressure float switch 7 will float due to buoyancy, thereby transmitting the floating signal to the first controller 8. The first controller 8 controls the submersible pump 6 to perform extraction work according to the signal to ensure timely extraction of wastewater. After the submersible pump 6 works, with the help of the design of the time relay 9, the first controller 8 can shut down the submersible pump 6 according to the end of the time relay 9 after each start of the submersible pump 6, effectively extending the work of the submersible pump 6, and ensuring that the water level of the wastewater in the pit 5 will drop significantly after each extraction, effectively reducing the frequent start and stop of the submersible pump 6, and ensuring the service life of the submersible pump 6.

[0052] When the submersible pump 6 is working normally, the pressure sensor 13 detects that the pressure in the sewage pipe 12 is abnormally reduced, and the signal can be transmitted to the second controller 16. After receiving the signal, the second controller 16 can control the first solenoid valve 100 and the third solenoid valve 140 to be closed, and control the fourth solenoid valve 150 and the second solenoid valve 110 to be opened. When the second controller 16 controls the high-pressure water pump to work, the high-pressure water pump can transport the clean water from the clean water tank to the backwash inlet pipe 15. The clean water can perform high-pressure backwashing on the submersible pump 6 along the pipeline to clean the dirt and impurities accumulated inside the submersible pump 6, ensure the normal operation of the submersible pump 6, and avoid damage to the submersible pump 6. Finally, the sewage source can pass through The backwash outlet pipe 11 flows into the water collecting tank 17. After the high-pressure backwash is completed, the second controller 16 can control the fourth solenoid valve 150 and the second solenoid valve 110 to close, and control the first solenoid valve 100, the third solenoid valve 140 and the fifth solenoid valve 190 to open, so as to cause the sewage in the water collecting tank 17 to be discharged into the pit 5 through the return pipe 19, which is conducive to the extraction and treatment of sewage together with wastewater. When the sewage is discharged, the design of the filter plate 18 can block impurities or debris from being retained in the first chamber 20, preventing dirt from clogging the submersible pump 6 again, and the blocked dirt can be cleaned regularly by manual follow-up to ensure normal filtration in the water collecting tank 17.

[0053] It should be noted that when a backwashing operation is completed, if the pressure sensor 13 detects abnormal pressure in the sewage pipe 12 again within a short period of time, the second controller 16 can be used to control each device to perform a second high-pressure backwash, and at the same time, the sound and light alarm 24 can be used to alarm to warn the staff to check and repair in time to avoid blockage of the submersible pump 6, which causes wastewater to be not discharged in time and overflow and flow everywhere. At the same time, it also avoids damage to the submersible pump 6 and ensures the normal service life of the submersible pump 6.

[0054] It should be noted that this article only provides a physical architecture for realizing automatic drainage of small pits. It only seeks to protect the physical structure and does not involve systemic protection. The introduction of the system proposed in this article is only for the purpose of supplementing the feasibility and authenticity of this application. Although the existing programming software and system programs are not described in detail in this article, they are already well known and applied by those skilled in the art and can be implemented in conjunction with the physical structure of this article.

[0055] Throughout this specification, terms such as "one embodiment," "some embodiments," and "specific embodiments" mean that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0056] Although the embodiments of the present invention have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and purpose of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. An automatic drainage device for a small pit, characterized in that: The invention comprises a first bracket (1) mounted on a wall surface, a second bracket (2), a first distribution box (3) and a second distribution box (4), and a submersible pump (6) arranged in a ground pit (5), wherein a low-pressure float switch (7) located inside the ground pit (5) is fixedly mounted on the first bracket (1), a filter assembly is arranged on the second bracket (2), and a first controller (8) electrically connected to the low-pressure float switch (7) and a time relay (9) electrically connected to the first controller (8) and the submersible pump (6) are arranged in the first distribution box (3), a water inlet of the submersible pump (6) is connected to a water suction pipe (10) and a backwash outlet pipe (11) through a three-way pipe, a first solenoid valve (100) is installed on the water suction pipe (10), and a second solenoid valve (100) is installed on the backwash outlet pipe (11). (110), one end of the backwash outlet pipe (11) is arranged above the filter assembly, and the outlet of the submersible pump (6) is connected to a sewage discharge pipe (12), the sewage discharge pipe (12) is provided with a pressure sensor (13), and the end of the sewage discharge pipe (12) away from the outlet of the submersible pump (6) is connected to a sewage discharge pipe (14) and a backwash inlet pipe (15) through a three-way pipe, the sewage discharge pipe (14) is provided with a third solenoid valve (140), the backwash inlet pipe (15) is provided with a fourth solenoid valve (150), and the second distribution box (4) is provided with a second controller (16) electrically connected to the pressure sensor (13), the first solenoid valve (100), the second solenoid valve (110), the third solenoid valve (140) and the fourth solenoid valve (150).

2. The automatic drainage device for a small pit according to claim 1, characterized in that: The filter assembly comprises a water collecting tank (17) mounted on the second bracket (2), a filter plate (18) arranged in the water collecting tank (17), a return pipe (19) connected to the bottom of the water collecting tank (17), and a fifth solenoid valve (190) mounted on the return pipe (19), wherein the fifth solenoid valve (190) is electrically connected to the second controller (16), and one end of the backwash outlet pipe (11) is arranged at an opening at the top end of the water collecting tank (17).

3. The automatic drainage device for a small pit according to claim 2, characterized in that: The inner cavity of the water collecting box (17) is provided with an inclined ramp, the bottom of the filter plate (18) is plugged into the inclined ramp, and the inner cavity of the water collecting box (17) is divided into a first chamber (20) and a second chamber (21) by the filter plate (18), one end of the backwash outlet pipe (11) is provided at the opening of the first chamber (20), and one end of the return pipe (19) is connected to the second chamber (21).

4. The automatic drainage device for a small pit according to claim 2, characterized in that: A guide groove is provided on the inner wall of the water collecting box (17), the filter plate (18) is arranged in the guide groove, and a handle is connected to the top of the filter plate (18).

5. The automatic drainage device for a small pit according to claim 1, characterized in that: It also includes an electricity storage device (22) installed on the wall surface and solar panels (23) distributed on the roof, wherein the electricity storage device (22) is electrically connected to the solar panels (23), the first controller (8) and the second controller (16).

6. The automatic drainage device for a small pit according to claim 1, characterized in that: An audible and visual alarm (24) is fixedly mounted on the top of the second distribution box (4), and the audible and visual alarm (24) is electrically connected to the second controller (16).

7. The automatic drainage device for a small pit according to claim 1, characterized in that: The pit (5) comprises a water flow section and a circular groove area, the submersible pump (6) is arranged in the circular groove area, and a recessed groove is provided in the circular groove area, and one end of the water suction pipe (10) is arranged in the recessed groove.

8. The automatic drainage device for a small pit according to claim 1, characterized in that: The low-pressure float switch (7) is arranged in the water flow section, and the model of the low-pressure float switch (7) is a P45 low-pressure float switch.

9. The automatic drainage device for a small pit according to claim 8, characterized in that: One end of the backwash water inlet pipe (15) is connected to a high-pressure water pump, and the water inlet of the high-pressure water pump is connected to a clean water tank through a pipeline.

10. The automatic drainage device for a small pit according to claim 1, characterized in that: A wire threading tube for wiring is provided on the surface of the wall.

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